A machine tool which performs machining, such as cutting, by moving a tool relative to a workpiece is known in a conventional technique. In such a machine tool, a numerical control-type machine tool is known which specifies a path of a tool by coordinates of a predetermined axis or the like and machines a workpiece by automatically moving the tool with respect to a workpiece. A tool used to machine a workpiece is appropriately selected depending on a machining shape of the workpiece. For example, when a groove portion is formed on a surface of a workpiece, a flat end mill or the like is used as a tool. In addition, when a plurality of types of machining is performed on a single workpiece, the machining can be performed by exchanging tools according to machining shapes of the workpiece.
The patent literature 1 discloses a machine tool which selects an optimum using tool based on various condition data for machining a workpiece. The machine tool includes an automatic tool allocation determination means which allocates a tool to a tool station of edged tools and an automatic programming device of the machine tool which automatically generates a machining program. The automatic programming device determines when an optimum tool is different from a tool allocated by the machining program to a last workpiece, whether the last allocated tool can be used in place of the optimum tool. Further, it is disclosed that the automatic programming device allocates a substitute tool when the last allocated tool can be used in place of the optimum tool.
Patent literature 1: Japanese Laid-open Patent Publication No. 4-25344